Global positioning systems (GPS) typically consist of a device including a GPS receiver and multiple GPS satellites. The GPS receiver is configured to receive and decode GPS signals broadcast from the GPS satellites in order to determine a location of the device. Each of the GPS satellite signals are transmitted with a satellite-specific encoding, which can be used by a GPS receiver to identify the broadcasting GPS satellite. The GPS receiver is able to calculate the location of the device by decoding the satellite signal, identifying the broadcasting GPS satellites, and performing a series of computations on the data extracted from the decoded signals.
Many devices today include GPS receivers and support applications that provide location based services. Typically, the GPS systems samples a GPS signal in the range of 30 seconds in order to accurately decode the GPS signal and identify the broadcasting GPS satellites. Unfortunately, sampling GPS signals is a power intensive process and many location-based applications available today on mobile devices require regular or continuous location sensing. Thus, while GPS receivers often provide the most accurate and reliable location information available to a mobile device, it is often the case that other sources are preferred. For example, mobile devices may obtain the location information from one of a variety of sources, including GPS receivers, cell-tower signals, FM radio signals, and/or WiFi signatures.